International Medical Journal Vol. 21, No. 1, pp. 83 - 85 , February 2014 SHORT COMMUNICATIONS In vitro Study of Erosive Effects of Commercial Soft Drinks on Surface Microhardness of Tooth-Colored Restorative Materials Zeenty F. Mat Yaman, Norhayati Luddin, Mohammad Khursheed Alam ABSTRACT Background: An increase in soft drinks consumptions raised the issue among dentists namely regarding its effect on the tooth-colored restorative materials. Objectives: The objective of this in vitro study were to measure the pH of a commercial soft drink and to evaluate the erosive effect of the soft drink on the surface microhardness of three types of tooth-colored restorative materials (microhybrid compos- ite, polyacid modified resin composites and ormocers. Methods: Ten disc-shaped specimens were prepared for each of three tooth-colored restorative materials (n = 30), which were divided into control and experimental groups consisting of 15 specimens each. The control group remained in artificial saliva and both groups were incubated at 37℃. The experimental group was immersed alternately for 5 seconds in cola soft drink, followed by artificial saliva, repeated for 10 cycles per day for 1 week. The surface microhardness was measured using a Vickers hardness tester and the results were analyzed using Mann-Whitney test and Kruskal-Wallis tests. The statistical level was accepted at p < 0.05. Results: Cola soft drink has PH of 2.5. All the materials tested, except for compomers showed reduced surface microhard- ness after immersion in cola soft drinks with the microhybrid composites showed a significant reduction. Conclusion: Cola soft drink has a low pH value that can reduce the physical performance of tooth-colored restorative mate- rials. However, this study found that only certain tooth-colored restorative materials were affected by the cola soft drink. KEY WORDS Cola soft drink, dental erosion, resin composite, compomer, ormocers, tooth-colored restorative materials, dental material, surface microhardness Received on October 1, 2012 and accepted on April 8, 2013 School of Dental Sciences, Universiti Sains Malaysia Kubang, Kerian, 16150, Kelantan, Malaysia Correspondence to: Norhayati Luddin (e-mail: norhayati @ kck.usm.my) 83 INTRODUCTION Nowadays, commercial soft drinks consumption is becoming popular especially among teenagers and young adults. The continuing increase in soft drink consumption among the adolescents raised a national concern, both on general and dental health. One of the most common dental related problems associated with consumption of soft drink is dental erosion. Dental erosion is defined as a physical result of pathologic, chronic and localized loss of hard tissues from the tooth surface by a chemical process without bacterial involvement 1) . The intrinsic and extrinsic etiology factors responsible for dental ero- sion are well-understood chemical events leading to initial mineral dissolution, softening and eventual loss of the dental surface 2) . Most soft drinks contain one or two common food acidulants-phosphoric acid and citric acid that contribute to the low pH value, thus cause dental erosion. Dental erosion can cause detrimental effect to the tooth structure such as hypersensitivity, or in severe cases, it may lead to pulp expo- sure and tooth fracture. Besides that, the clinical performance of the restorative materials is affected by erosion. A few studies reported that acidic condition degraded glass ionomer cements and restorative com- posite. Wongkhantee and co-workers 3) conducted a study to evaluate the effect of acidic food and drinks on surface hardness of various sub- strates such as enamel, dentin, universal composite, microfilled com- posite, conventional glass ionomer, resin modified glass ionomer and polyacid-modified resin composites. They reported that the cola soft drink significantly reduced surface hardness of enamel, dentine, micro- filled composite and resin modified glass ionomer (p < 0.05). There was also a study conducted by Prakki and co-workers 4) evaluated the influence of pH environment on polymer based dental material properties. They concluded that very low acidic medium (pH < 2.0) accelerated dental composite hydrolysis and caused quick micro-structural damage. Another study did by McKenzie and co- workers 5) investigated the effect of Coca-Cola and fruit juices on the surface hardness of glass ionomers and compomers. However, the authors reported that the conventional glass-ionomers dissolved com- pletely in apple juice and orange juice, but survived in Coca-Cola. Fruit juices were thus shown to pose a greater erosive threat to tooth- colored restorative materials than Coca-Cola. As to our knowledge, no study has been done to evaluate the physical performance of another new type of tooth-colored restora- tive material that is organically modified ceramics or also known as ormocers. This study needs to be conducted in order to increase pub- lic awareness on the dental erosive potential of certain commercial soft drinks to make the healthier choice. The general objective of this in vitro study generally was to assess the erosive effects of commercial soft drinks on tooth-colored restorative materials. Specifically, it were to determine the pH level of commercial soft drink and to compare the microhardness of differ- ent tooth-colored restorative materials (microhybrid composite, poly- acid modified resin composites and organically modified ceramics) C 2014 Japan International Cultural Exchange Foundation & Japan Health Sciences University